Why? I thought free made everything delicious. Apparently not, which I guess is good news. I"m fine with being wrong.

What I don't think I'm wrong about is that what really sells well, what readers are interested in, is very mainstream.

If suddenly vampires are it, then everyone chases vampires. If it's whips and handcuffs, then that's what's bright and shiny. If it's espionage, or police procedural, or paranormal then that works. What it has to do is fall within the normal understanding of that thing.